The invention relates to apparatus and a method for the formation and/or enlarging of generally horizontal bores for the mining of coal, ore and the like. In the past, coal has often been mined with conventional auger-miners (such as shown in U.S. Pat. No. 2,784,955) and the like by boring a generally circular cross-section bore into a coal seam. Bores must be spaced far enough from each other to make sure that collapse of the bores does not occur, however, in many older mines these bores are much farther apart than necessary. In mining in such a method, generally the maximum amount of coal is not recovered from an area both because of the shape of the bores and because the area in between bores is wasted.
According to the present invention, apparatus and a method are provided for enlarging pre-existing bores both by changing the cross-sectional shape and the cross-sectional area thereof, and additionally for forming new bores and removing ore during both movement of the mining machine into and out from the bore (the invention is also applicable to underground mining). Conventional mining machines, such as shown in U.S. Pat. Nos. 2,784,955, 3,105,677, 3,121,558, 3,190,698, 3,210,123 and 3,333,898, are capable only of mining during movement of the mining machine into a formation to form a bore therewith, and not during withdrawal of the machine. The machine and method according to the present invention result in the advantages of less wasted set-up time and the like for mining with a machine of a given size, the mining of larger bores with a machine of a given size, and the capacity to retrieve coal, ore, and the like from bores that have previously been made, which coal, ore, and the like has been up to now unusable. All of this can be accomplished with safety since operators are never required to go into the bores being formed or enlarged.
According to the present invention, a mining machine is provided that has a non-rotatable body member in line with a conveying means, and a pair of wing-cutters. The wing-cutters are generally formed by rotatable cutting drums pivotally mounted on lever arms to the body member, and generally driven by cutting chains or the like. During movement of the machine into a pre-existing bore, the wing-cutters are in a position substantially in line with the body member and the conveyor, the mining machine as a whole presenting a cross-sectional area about the same as or slightly less than that of the pre-existing bore. Once far enough into the bore, the wing-cutters are then moved to a position wherein they are disposed outwardly with respect to the body member, and they are held in that outward position while the rotatable drum cutting portions thereof are normally rotated in a direction outwardly from the body member, each drum rotating in a different direction than the other. The machine is withdrawn with the wing-cutters in this position, and cutting takes place the whole time during withdrawal, the coal or the like being thrown toward the conveying means, which preferably comprises an auger.
For both in and out cutting, preferably a pilot cutting head is provided for the machine, in line with the body member and the conveying means. The pilot head preferably is a conventional type such as disclosed in U.S. Pat. No. 2,784,955, the disclosure of which is hereby incorporated by reference in the present application. Also, the chains which drive the cutting drums preferably are cutting chains and they may be arranged so that a circular hole of diameter D cut by the pilot cutting head is enlarged during in-cutting to a square hole of dimension D sides.
It is the primary object of the present invention to provide an improved method and apparatus for the mining of coal, ore, and the like. This and other objects of the invention will become apparent from an inspection of the detailed description of the invention, and from the appended claims.